Focal adhesions are important subcellular structures that are composed of many signaling and scaffolding proteins. They serve not only for anchoring the cell to the substratum but they are also important signaling centers that regulate various cellular behavior such as migration, invasiveness, proliferation and survival. Focal adhesion signaling needs to be strictly regulated because alteration in activity or expression of many focal adhesion proteins leads to tumorogenesis and metastasis formation. One of the most important scaffolding protein associated with focal adhesion is p130Cas. The importance of p130Cas in regulation of cell migration and invasiveness has been well established. P130Cas also plays important role in regulation of cell survival and proliferation. Moreover, high protein levels of human ortholog of p130Cas - BCAR1, has been linked to more aggressive breast tumors and poor prognosis. During my doctoral studies, I focused on the role of p130Cas in integrin signaling. At the beginning we characterized the role of tyrosine 12 phosphorylation within its SH3 domain. We confirmed that this phosphorylation is increased in Src527F transformed mouse embryonic fibroblasts compared to non-transformed counterparts and also in some human cancer cell lines. We showed that this phosphorylation..